This is a note to let you know that I've just added the patch titled NFSv4 fix CLOSE not waiting for direct IO compeletion to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: nfsv4-fix-close-not-waiting-for-direct-io-compeletion.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From d03727b248d0dae6199569a8d7b629a681154633 Mon Sep 17 00:00:00 2001 From: Olga Kornievskaia <olga.kornievskaia@xxxxxxxxx> Date: Wed, 24 Jun 2020 13:54:08 -0400 Subject: NFSv4 fix CLOSE not waiting for direct IO compeletion From: Olga Kornievskaia <olga.kornievskaia@xxxxxxxxx> commit d03727b248d0dae6199569a8d7b629a681154633 upstream. Figuring out the root case for the REMOVE/CLOSE race and suggesting the solution was done by Neil Brown. Currently what happens is that direct IO calls hold a reference on the open context which is decremented as an asynchronous task in the nfs_direct_complete(). Before reference is decremented, control is returned to the application which is free to close the file. When close is being processed, it decrements its reference on the open_context but since directIO still holds one, it doesn't sent a close on the wire. It returns control to the application which is free to do other operations. For instance, it can delete a file. Direct IO is finally releasing its reference and triggering an asynchronous close. Which races with the REMOVE. On the server, REMOVE can be processed before the CLOSE, failing the REMOVE with EACCES as the file is still opened. Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx> Suggested-by: Neil Brown <neilb@xxxxxxxx> CC: stable@xxxxxxxxxxxxxxx Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/nfs/direct.c | 13 +++++++++---- fs/nfs/file.c | 1 + 2 files changed, 10 insertions(+), 4 deletions(-) --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -396,8 +396,6 @@ static void nfs_direct_complete(struct n { struct inode *inode = dreq->inode; - inode_dio_end(inode); - if (dreq->iocb) { long res = (long) dreq->error; if (dreq->count != 0) { @@ -409,7 +407,10 @@ static void nfs_direct_complete(struct n complete(&dreq->completion); + igrab(inode); nfs_direct_req_release(dreq); + inode_dio_end(inode); + iput(inode); } static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) @@ -539,8 +540,10 @@ static ssize_t nfs_direct_read_schedule_ * generic layer handle the completion. */ if (requested_bytes == 0) { - inode_dio_end(inode); + igrab(inode); nfs_direct_req_release(dreq); + inode_dio_end(inode); + iput(inode); return result < 0 ? result : -EIO; } @@ -957,8 +960,10 @@ static ssize_t nfs_direct_write_schedule * generic layer handle the completion. */ if (requested_bytes == 0) { - inode_dio_end(inode); + igrab(inode); nfs_direct_req_release(dreq); + inode_dio_end(inode); + iput(inode); return result < 0 ? result : -EIO; } --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -82,6 +82,7 @@ nfs_file_release(struct inode *inode, st dprintk("NFS: release(%pD2)\n", filp); nfs_inc_stats(inode, NFSIOS_VFSRELEASE); + inode_dio_wait(inode); nfs_file_clear_open_context(filp); return 0; } Patches currently in stable-queue which might be from olga.kornievskaia@xxxxxxxxx are queue-4.19/nfsv4-fix-close-not-waiting-for-direct-io-compeletion.patch